Process for preparing an ester



Patented Oct. 27, 1931 UNITED STATES PATENT OFFICE IVAN GUIBELMANN AND CLYDE 0. HENKE, OF SOUTH MILWAUKEE, WISCONSIN, AS- SIGNOIRS TO THE NEWPORT COMPANY, OF CARROLLVILLE, WISCONSIN, A COREORA- TION OF DELAWARE PROCESS FOR PREPARING AN ESTER No Drawing. Application filed July 2,

This invention relates to a process of prepariing ethyl abietate from rosin or abietic ac1 It is an object of this invention to provide .8 a method of preparing ethyl abietate from abietic acid containing material and ethyl alcohol in a more economically practical manner than has hitherto been proposed. Other and further important objects of 1 this invention will become apparent from the following description and appended claims.

There have been methods described for preparing this ester employing absolute alcohol, abietic acid and concentrated sulfuric acid. The present invention employs an alcohol of weaker concentration than absolute alcohol, thus resulting in a more economical use of the raw material.

Our process employs ordinary alcohol of 95% strength, or a suitably denatured alcohol of similar strength, together with a condensing agent, as for example, concentrated sulfuric acid, oleum, hydrochloric acid and the like. The abietic acid containing material can be either a rosin or abietic acid in substantially pure form. The impure abietic acid as found in rosin tends to produce a poorer grade of ester.

Without limiting our invention to any particular procedure, the following example, in which parts by weight are given, will serve to illustrate our method in its preferred form.

ExampZe.-To 2400 parts of 95% alcohol are added 360 parts of 25% oleum and 800 parts of abietic acid. This mixture is refluxed until about 90% of the abietic acid is esterfied. There is then added 3000 parts of water and the alcohol distilled off. The residue comprises ethyl abietate, about 10% of quality of ethyl abietate. Instead of fracgrain Serial No. 290,026.

tional distillation the calculated amount of alkali may be added and then the ethyl abietate distilled from the sodium abietate, which remains as a residue. sodium abietate may be removed from the ester in water solution, in which the ester is insoluble.

By this procedure about an 85% yield of ethyl abietate is secured and by reusing the abietic acid left in the fractionation still the y1eld may be brought up to over 95%.

Ethyl abietate has been produced from rosin in exactly the same way but the product contains some resene from the rosin, thereby making the product less pure than where abietic acid itself is used as starting material.

In carrying out the above process the ratio of reagents used may be varied within rather wide limits, and instead of employing 25% oleum, oleum of other strengths may be employed. Likewise, instead of oleum, con- 'centrated sulfuric acid or hydrochloric acid may be used. The speed of the reaction may be increased by working at elevated temperatures under pressure. Moreover, in the esterlfication process the reaction may be stopped when more or less than 90% of the abietic acid is esterified. For example, the

If desired the reaction may be stopped when 7 5 to of the abietic acid has been esterified, the ester separated by fractional distillation from the abietic acid and the abietic acid again put in the process. The method of isolating the ester from the reaction mass may likewise be varied, as for example, after diluting the mass with water, the ester layer may be separated before distilling off the alcohol, washed and then fractionally distilled.

. This invention involves the improvement inmethod of'procedu're which makes possible the use of 95% alcohol or an alcohol of weaker strength than absolute alcohol to perform the esterification.

YVe are awarethat numerous details of the process may be varied through a wide range without departing from the principles of this invention, and we, therefore, do not purpose limiting the patent granted hereon otherwise'than necessitated by the prior art.

' recovering the ethyl abietate.

We claim as our invention: 1. The process of preparing ethyl abietate, which comprises heating a commercial grade of ethyl alcohol of less strengththan abso;

lute with abietic acid. containing material in the presence of a condensing agent to effect esterification and recovering the ethyl abie tate.

2. The process of preparing ethyl abietate, which comprises heating-ethyl alcohol'of. ap-

proximately 95% strength with abietic acid containing material in the presenceof a condensing agent to effect esterification andrecovering the ethyl abietate. s c, Q

3. The process of preparing ethyl abietate, whichcomprisesheating a commercial grade of ethyl alcohol of less strength than absolute with abietic acid containing material in the presence of concentrated sulfuric acid as condensingagent to effect esterification and recovering the ethyl abietate. 1; 1 v

4. The process of preparing ethyl abietate,"

which comprisesheating a commercial grade of ethyl alcohol of less. strength than abso- 2 5 lute with abietic' acid in the presence ofa condensing agent'to eflect esterification and 5. The processof preparing ethyl abietate,

. which comprises heating ethyl alcohol. ofapproximately 95% strength'with abietic' acid I in the presence of a condensing agent to effeet esterifi'cation and recovering the ethyl abietate. f v

6. The process of ethyl alcohol of less strength than absolute withabietic' acid, in the presence of con'cen trated sulfuric acid as-condensingagent t efiect esterification and recovering'the ethyl abietate. H

7. Thefprocess'of preparingethyl 'abietate,

. esterification operations.

7 ofpreparingethyl abietate, which comprises heating a commercial grade .10. In the process of preparing ethyl abietate by the esterification of ethyl alcohol and abietic acid in the presence of a condensing agent, the steps of stopping the reaction short of complete esterification, recovering abietic acid fromthe reactionimass and reusing said abietic acid in subsequentesterification operations.

I 11. In the process of preparing ethyl'abietateby the esterificationof ethyl. alcohol and abietic acid in the presence ofiacondensing agent the stepsof stopping the reaction short of complete esterification, diluting the reaction. mass to form a layer containing ethyl abietate and abietic acid, fractionally dis tilling the ethyl abietate layer ziniv acuo to separate the ethyl abietatelroni the abietic acid and reusing the abietica'cid in further 12. The process-of preparing ethyl'abietate which comprisesrefiuxing a mixture of 2400 parts of 95% ethyl alcohol, 800 parts of abietic acid and 360 parts'of 25% oleum until about of the abietic acidis esterified.

13. In the process ofpreparing ethyl abietate by heating abietic acid containing material with ethyl alcohol in the presenceof a which comprises subjectingapproximately ethyl alcohol and abietic acid to an elevated temperature in the presence'of 25% oleum to elfect 'esterification, dilutin the re; action mass'jwith water, separating t e ethyl abietate from the diluted mass and fractionally distilling to obtain ethyl abietate in a h 'e rur tr. r i

'8. The processfof; reparingethyl abietate,

whichromprises re uxing a mixture of95%i 1 p r ethylalcohol; concentrated sulfuric acid and abietic'acid to'jefl'ect'"esterificatiom diluting I the mass with water to formlayers,separa ti'ng one of said layers containin ethyl abietate and abietic acid and recoverlng the ethyl abietate.

.9, t The process ofprep'aringethyl abietate;

which comprises refluxinga mixture of 95% I ethyl alcohol, concentrated sulfuric acid" and I abietic acid to effect esterification, diluting the mass with water to form layers, separating one of said layers 'containi'ng ethylabia tate and abietic acidvand fractionally} distillingimvacuo to recover the ethyl; abietate; 

